Murine ortholog of the human disrupted-in-schizophrenia 1 gene

ABSTRACT

The present invention features Disc1 polypeptides, Disc1 nucleic acids, and recombinant Disc1 altered mice. The Disc1 amino acid sequence of SEQ ID NO: 1 and the nucleic acid sequence of SEQ ID NO: 2 provide the mouse ortholog to the human DISC1 amino acid sequence and nucleic acid sequence.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication No. 60/383,191, filed May 24, 2002, hereby incorporated byreference herein.

BACKGROUND OF THE INVENTION

The references cited throughout the present application are not admittedto be prior art to the claimed invention.

Schizophrenia is a debilitating psychiatric disorder characterized bydisordered thinking, hallucinations, and cognitive dysfunction. (Franceset al. ed. Diagnostic and Statistical Manual of Mental Disorders. FourthEdition ed. 1994, American Psychiatric Association: Washington, D.C.)Family, twin and adoption studies have suggested that ˜50% of the riskof developing schizophrenia is genetic.

The human disrupted-in-schizophrenia 1 (DISC1) and thedisrupted-in-schizophrenia 2 (DISC2) genes have been identified as genesthat may play a role in susceptibility to psychiatric illness. (Millaret al. (2000) Hum. Mol. Genet., 9(9), 1415-1423.)

DISC1 and DISC2 genetic abnormalities have been associated withschizophrenia and related disorders. In a single Scottish family, theDISC1 open reading frame was found to be truncated by a balanced(1:11)(q42.1;q14.3) translocation. In this family, the translocationsegregates not only with schizophrenia, but with other major mentalillnesses, including schizoaffective disorder, bipolar disorder, andunipolar depression. The observed familial clustering of diseases istypical of sporadic schizophrenia. (Millar et al. (2000) Hum. Mol.Genet., 9(9), 1415-1423.)

Additional support for DISC1 playing a role in psychiatric illness comesfrom its chromosomal location. DISC1 was found to map next to thechromosomal marker D1S251, which localizes DISC1 to a region implicatedin psychiatric illness. (Millar et al. (2001) Mol. Psychiatry, 6(2),173-178.)

DISC1 is estimated to be 300 kb and contains 13 exons. (Millar et al.(2001) Mol. Psychiatry, 6(2), 173-178.) An identified open reading forDISC1 encodes a putative protein of 854 amino acids. (Millar et al.(2000) Hum Mol Genet, 9(9), 1415-1423.) The putative DISC1 proteincontains an N-terminal region (amino acids 1-147) predicted to consistof one or more globular domains and a C-terminal region predicted toconsist entirely of α-helix interspersed with several short loops.(Millar et al. (2000) Hum Mol Genet, 9(9), 1415-1423.)

DISC2 overlaps with DISC1 exon 9. (Millar et al. (2001) Mol Psychiatry,6(2), 173-178.) DISC2 has been suggested to specify a non-coding RNAmolecule that is antisense to DISC1. (Millar et al. (2000) Hum MolGenet, 9(9), 1415-1423.)

SUMMARY OF THE INVENTION

The present invention features Disc1 polypeptides, Disc1 nucleic acids,and recombinant Disc1 altered mice. The Disc1 amino acid sequence of SEQID NO: 1 and the nucleic acid sequence of SEQ ID NO: 2 provide the mouseortholog to the human DISC1 amino acid sequence and nucleic acidsequence.

SEQ ID NO: 1 provides a reference sequence for Disc1 polypeptides. Disc1polypeptides contain a region of at least 18 contiguous amino acids thatis present in SEQ ID NO: 1. Disc1 polypeptides may contain additionalregions beyond 18 contiguous amino acids present in SEQ ID NO: 1 and maycontain amino acid regions not present in SEQ ID NO: 1.

SEQ ID NO: 2 provides a reference sequence for Disc1 nucleic acids.Disc1 nucleic acids contain a region that encodes a Disc1 polypeptide orcontains at least 30 contiguous nucleotides that is present in SEQ. ID.NO. 2 or the complement thereof. Such Disc1 nucleic acids may containadditional regions present, or not present, in nucleic acid encoding forDisc1, or present in SEQ. ID. NO. 2 or the complement thereof.

Thus, a first aspect of the present invention describes a purified Disc1polypeptide. The polypeptide comprises at least 18 contiguous aminoacids of SEQ ID NO: 1.

A “purified polypeptide” represents at least 10% of the total proteinpresent in a sample or preparation. In preferred embodiments, thepurified polypeptide represents at least about 50%, at least about 75%,or at least about 95% of the total protein in a sample or preparation.Reference to “purified polypeptide” does not require that thepolypeptide has undergone any purification and may include, for example,chemically synthesized polypeptide that has not been purified.

Another aspect of the present invention describes a recombinant nucleicacid that either:

-   -   a) encodes a Disc1 polypeptide and is transcriptionally coupled        to an exogenous promoter;    -   b) is a Disc1 nucleotide sequence or the complement thereof and        is attached to a solid support;    -   c) is provided by SEQ ID NO: 2;    -   d) is provided by a modified SEQ ID NO: 2 sequence; or    -   e) is provided by SEQ ID NO: 4.

A recombinant nucleic acid is a nucleic acid that contains two or morenucleic acid regions not naturally associated with each other and/or ispresent in a different environment than found in nature. Examples ofrecombinant nucleic acid includes nucleic acid containing a codingregion and one or more regulatory elements not naturally associated withthe coding region, exons joined together in DNA, expression vectors, andnucleic acid attached to a solid support. Recombinant nucleic acidcontaining recombined regions can be present inside a genome or mayexist outside of the genome.

Another aspect of the present invention describes a recombinant cellcomprising a nucleotide sequence encoding a Disc1 polypeptide that istranscriptionally coupled to an exogenous promoter. The exogenouspromoter is a promoter not naturally associated with the nucleotidesequence. The cell contains an RNA polymerase that recognizes thepromoter.

Another aspect of the present invention describes a recombinant cellmade by a process comprising the step of introducing into a mousecellular genome a recombinant nucleic acid encoding at least 18contiguous bases of SEQ ID NO: 1.

Another aspect of the present invention features a purified antibodypreparation comprising an antibody that selective binds to a polypeptideof SEQ ID NO: 1 over human DISC1 polypeptide (SEQ ID NO: 5). Theantibody may also bind to fragments and/or variants of SEQ ID NO: 1.

A “purified antibody preparation” is a preparation where at least 10% ofthe antibodies present bind to a polypeptide of SEQ ID NO: 1. Thepreparation may contain polyclonal or monoclonal antibodies. Inpreferred embodiments, antibodies binding to Disc1 represent at leastabout 50%, at least about 75%, or at least about 95% of the totalantibodies present. Reference to “purified antibody preparation” doesnot require that the antibodies in the preparation have undergone anypurification.

Another aspect of the invention describes a recombinant Disc1 alteredmouse. The mouse comprises an alteration in an allele encoding a Disc1polypeptide comprising at least 20 contiguous amino acids of SEQ ID NO:1, wherein the alteration substantially reduces, or increases, fulllength expression of Disc1 from the allele. The presence of nucleic acidencoding at least 20 contiguous amino acids of SEQ ID NO: 1characterizes the nucleic acid as providing a Disc1 allele.

Another aspect of the present invention features a method for screeningfor a compound able to bind to a Disc1 polypeptide. The method involvesthe step of measuring the ability of the compound to bind to thepolypeptide.

Other features and advantages of the present invention are apparent fromthe additional descriptions provided herein including the differentexamples. The provided examples illustrate different components andmethodology useful in practicing the present invention. The examples donot limit the claimed invention. Based on the present disclosure theskilled artisan can identify and employ other components and methodologyuseful for practicing the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. Human DISC1 (“oth:human”; SEQ ID NO: 5) and the murine ortholog(“oth:mouse”; SEQ ID NO: 1) were aligned by Clustal W alignment. Therewas 56% identity and 14% similarity (excludes identical amino acids)between the two proteins. An InterPro domain search revealed a weaksuggestion of a tropomyosin (amino acids 349-366; and amino acids556-581) and a bipartite nuclear localization signal (amino acids331-348) in the human sequence (Apweiler et al. (2000) Bioinformatics,16(12), 1145-1150). The mouse sequence had a low homology to DUF232(amino acids 454-477). Arrow indicates translocation breakpoint.Bioinformatic analysis revealed three leucine zipper motifs conservedbetween mouse (amino acids 454-475; amino acids 461-482; and amino acids603-624) and human (amino acids 458-479) (amino acids 465-486) (aminoacids 607-628).

FIGS. 2A, 2B, and 2C. Comparison of human DISC1 (“oth:human”; SEQ ID NO:6) and murine Disc1 nucleic acid (“oth:mouse”; SEQ ID NO: 2).

FIG. 3. Mouse Disc1 splice variant amino acid sequence (SEQ ID NO: 3).

FIG. 4. Mouse Disc1 splice variant encoding nucleic acid sequence alongwith a TGA stop codon (SEQ ID NO: 4).

FIG. 5. A BAC map of the Disc1 genomic region. Two BACs were identifiedusing the TIOR BAC end sequencing database. (Zhao et al. (2001) GenomeRes, 11(10), 1736-1745.) 418L11 contains sequences from 946-1446 of theTsnax gene. 236F19 contains nucleotides 1500-2410 of the Tsnax.Bac259E12 was identified by hybridization of a Disc1 probe (nucleotides2376-2490) against a mouse BAC library (Incyte).

DETAILED DESCRIPTION OF THE INVENTION

Disc1, the mouse ortholog to human DISC1, has been identified andcloned. Human DISC1 translocation has been associated with psychiatricdiseases such as schizophrenia, schizoaffective disorder, bipolardisorder, and unipolar depression.

The present invention include Disc1 polypeptides and nucleic acids.Disc1 polypeptides and nucleic acids have a variety of different usessuch as providing research tools for studying Disc1 polypeptide functionand expression in a cell; studying the involvement of Disc1 withpsychiatric diseases; identifying Disc1 nucleotide polymorphism(s); andcreating recombinant Disc1 deficient mice.

A recombinant Disc1 deficient mouse can be used, for example, as modelto examine the involvement of Disc1 with psychiatric diseases, and theability of compounds to compensate for the effect of a Disc1 alteration.

I. Disc1 Polypeptides

Disc1 polypeptides contain a region of at least 18 contiguous aminoacids that is present in SEQ ID NO: 1. Disc1 polypeptides have a varietyof uses, such as being used as an immunogen to produce antibodiesbinding to Disc1 and being used as a target to identify compoundsbinding to the Disc1.

The presence of at least 18 contiguous amino acids of SEQ ID NO: 1provides a unique structural tag for a Disc1 polypeptide and asufficient polypeptide region to achieve a useful purpose. The at least18 contiguous amino acids can, for example, provide an immunogen togenerate an antibody. In different embodiments the Disc1 polypeptidecontains a tag of at least 20 contiguous amino acids of SEQ ID NO: 1; atleast 40 contiguous amino acids of SEQ ID NO: 1, at least 80 contiguousamino acids of SEQ ID NO: 1; or comprises or consists of SEQ ID NO: 1.

Disc1 polypeptides may contain additional SEQ ID NO: 1 regions inaddition to a Disc1 tag and may contain amino acid regions not presentin SEQ ID NO: 1. Disc1 polypeptides include full length Disc1 of SEQ IDNO: 1, variants of SEQ ID NO: 1 containing a Disc1 tag, and chimericpolypeptides containing a Disc1 polypeptide and amino acid region(s) notfrom SEQ ID NO: 1.

Variants of SEQ ID NO: 1 containing a Disc1 tag include naturallyoccurring variants such as splice variants and/or polymorphic variants.SEQ ID NO: 3 provides the sequence of a splice variant that has an aminoacid alteration. Examples of SEQ ID NO: 1 variants are also provided inExample 2, Table 3, infra. The variants provided in Table 3 wereobtained from a splice variant and different PCR product reactions.

In additional embodiments concerning Disc1 polypeptide variants, SEQ IDNO 1: is modified with one or more of the following modifications:

-   amino acid 46: A to V;-   amino acid 58: G to D;-   amino acid 111: E to D;-   amino acid 214: F to L; and-   amino acid 231: C to R.    Preferred combinations of modifications correspond to those found in    a particular PCR product (amino acids 46, 58, 111 and 201 were from    one PCR product; amino acid 214 was from one PCR product; and amino    acids 231 and 397 was from a splice variant).

Chimeric polypeptides containing a Disc1 tag can contain non-Disc1regions chosen to achieve a particular purpose or to produce apolypeptide that can substitute for Disc1 or a fragment thereof.Particular purposes that can be achieved using appropriate non-Disc1regions include providing a marker for isolation and enhancing an immuneresponse.

In additional embodiments, the Disc1 polypeptide contains at least 18,at least 20, at least 40 or at least 80 contiguous amino acids where theencoding nucleic acid spans two or more exons. The amount of contiguousamino acids corresponding to a particular exon can vary. In differentembodiments the Disc1 polypeptide contains at least 9, at least 10, atleast 20, or at least 40 amino acids contiguous amino acidscorresponding to two or more different exons.

The amino acids sequences in SEQ ID NO: 1 encoded by different exons areassigned as follows: Exon 1 MQGGGPRDAPIHSPSHGA Exon 2SGHGLPPAVAPQRRRLTRRPGYMRSTAGSGIGFLSPAVGMPHPSSAGLTGQQSQHSQSKAGQCGLDPGSHCQASLVGKPFLKSSLVPAVASEGHLHPAQRSMRKRPVHFGVHSKNDSRQSEKLTGSFKPGDSGCWQELLSSDSFKSLAPSLDAPWNTGSRGLKTVKPLASSALNGPADIPSLPGFQDTFTSSFSFIQLSLGAAGERGEAEGCLPSREAEPLHQRPQEMAAEASSSDRPHGDPRHLWTFSLHAAPGLADLAQVTRSSSRQPECGTVSSSSDTVFSSQDASSAGGRGDQGGGWADAHGWHTLLREWEPMLQDYLLSNRRQLE Exon 3 VTSLILKLQKCQEKAVEDGDYDT Exon 4ETLRQRLEELEQEKGHLSWALPSQQPALRSFLGYLAAQIQVALHGATQ Exon 5AGSDDPEAPLEGQLRTTAQDSLPASITRRDWLIREKQQLQ Exon 6KEIEALQARMSALEAKEKRLSQELEEQEVLLRWPGCDLMALVAQMSPGQLQEVSKALGETLTSANQAPFHVEPPETLR Exon 7 LRERTKSLNLAVRELTAQ Exon 8VCSGEKLCSSLRRRLSDLDTRLPALLEAKMLALS Exon 9SCFSTAKELTEEIWALSSEREGLEMFLGRLLALSSRNSRRLGILKEDYLR CRQDLALQDAAH Exon 10TRMKANTVKCMEVLEGQLS Exon 11CRCPLLGRVWKADLETCQLLMQSLQLQEAGSSPHAEDEEQVHSTGEAAQTAALAVPRTPHPEEEKSPLQVLQEWDTHSALSPHCAAGPWKE Exon 12DSHIVSAEVGEKCEAIGVRLLHLEDQLLGAMYSHDEALF Exon 13SLQGELQTVKETLQAMILQLQPTKEAGEASASYPTAGAQETEA

Polypeptides can be produced using standard techniques including thoseinvolving chemical synthesis and those involving biochemical synthesis.Techniques for chemical synthesis of polypeptides are well known in theart. (See e.g., Vincent, in Peptide and Protein Drug Delivery, New York,N.Y., Decker, 1990.)

Biochemical synthesis techniques for polypeptides are also well known inthe art. Such techniques employ a nucleic acid template for polypeptidesynthesis. The genetic code providing the sequences of nucleic acidtriplets coding for particular amino acids is well known in the art.(See, e.g., Lewis GENES IV, p. 119, Oxford University Press, 1990.)Examples of techniques for introducing nucleic acid into a cell andexpressing the nucleic acid to produce protein are provided inreferences such as Ausubel, Current Protocols in Molecular Biology, JohnWiley, 1987-1998, and Sambrook et al., Molecular Cloning, A LaboratoryManual, 2^(nd) Edition, Cold Spring Harbor Laboratory Press, 1989.

II. Disc1 Antibodies

Antibodies recognizing Disc1 can be produced using a polypeptidecontaining SEQ ID NO: 1 or a fragment thereof as an immunogen.Antibodies recognizing Disc1 have different uses such as being used toidentify the presence of Disc1, to isolate Disc1 polypeptides, and tostudy Disc1 expression.

Techniques for producing and using antibodies are well known in the art.Examples of such techniques are described in Ausubel, Current Protocolsin Molecular Biology, John Wiley, 1987-1998; Harlow, et al., Antibodies,A Laboratory Manual, Cold Spring Harbor Laboratory, 1988; Kohler, etal., Nature 256:495-497, 1975; and Schweitzer et al. Current Opinion inBiotechnology 13:14-19, 2002.

III. Binding Assay

Disc1 polypeptides can be used in binding studies to identify compoundsbinding to the receptor. Preferably, binding studies are performed usingDisc1 expressed from a recombinant nucleic acid. More preferably,recombinantly expressed Disc1 consists of the SEQ. ID. NO. 1, SEQ. ID.NO. 3, or a modified SEQ. ID. NO. 1 containing one or more modificationsselected from the group consisting of:

-   amino acid 46: A to V;-   amino acid 58: G to D;-   amino acid 111: E to D;-   amino acid 214: F to L; and-   amino acid 231: C to R.

Binding assays can be performed using individual compounds orpreparations containing different numbers of compounds. A preparationcontaining different numbers of compounds having the ability to bind toa Disc1 polypeptide can be divided into smaller groups of compounds thatcan be tested to identify the compound(s) binding to the Disc1polypeptide.

Binding assays can be performed using Disc1 present in differentenvironments. Such environments include, for example, cell extracts andpurified cell extracts containing a Disc1 recombinant nucleic acid; andalso include, for example, the use of a purified Disc1 polypeptideproduced by recombinant means which is introduced into a differentenvironment.

IV. Disc1 Nucleic Acid

Disc1 nucleic acid contains a region encoding a Disc1 polypeptide orcontains at least 30 contiguous nucleotides present in SEQ ID NO: 2 orthe complement thereof. Disc1 nucleic acids have a variety of uses, suchas being used as a hybridization probe or polymerase chain reaction(PCR) primer to identify the presence of Disc1 variants and orthologs;being used as a hybridization probe to monitor Disc1 expression; beingused as an antisense nucleic acid to examine Disc1 functions; being usedfor recombinant expression of Disc1 polypeptides; and/or being used inthe construction of recombinant mice having an altered Disc1 allele.

The presence of a region that encodes a Disc1 polypeptide or contains atleast 30 contiguous nucleotides that is present in SEQ ID NO: 2 or thecomplement thereof provides a unique structural tag and a sufficientnucleic acid region to achieve a useful purpose. Examples of particularpurposes include providing a sequence that encodes a Disc1 polypeptideand/or providing a sequence that can selectively hybridize to Disc1 MRNAunder appropriate stringency conditions. Selective hybridizationindicates that the nucleic acid region can preferentially hybridize tomurine Disc1 MRNA over at least human DISC1 MRNA.

Disc1 nucleic acid may contain regions in addition to a region thatprovides the Disc1 tag. Additional regions include Disc1 related regionssuch as additional regions encoding for SEQ ID NO: 1 polypeptides orvariants thereof, additional SEQ ID NO: 3 regions or variants thereof,additional regions complementary to SEQ ID NO: 3 and variants thereof;and non-Disc1 related regions.

Non-Disc1 related regions are preferably chosen to achieve a particularpurpose. Examples of non-Disc1 related regions that can be used toachieve a particular purpose include capture regions that can be used aspart of a sandwich assay, reporter regions that can be probed toindicate the presence of the nucleic acid, expression vector regions,and regions encoding for immune enhancing polypeptides. Variants of SEQID NO: 1 are described above in Section I.

Variants of SEQ ID NO: 2 contain a Disc1 tag and include naturallyoccurring variants such as splice variants and/or polymorph variants ofSEQ ID NO: 2. SEQ ID NO: 4 provides the sequence of a splice variant.Examples of SEQ ID NO: 2 variants are also provided in Example 2, Table3, infra. The variants provided in Table 2 were obtained from a splicevariant and different PCR product reactions.

In additional embodiments concerning Disc1 nucleic acid variants, SEQ IDNO 2: is modified with one or more of the following modifications:

-   nucleotide 137: C to T;-   nucleotide 173: G to A;-   nucleotide 333: G to T;-   nucleotide 606: C to T;-   nucleotide 640: T to C;-   nucleotide 691: T to C; and-   nucleotide 1191: G to A.    Preferred combinations of modifications correspond to those found in    a particular PCR product (nucleotides 137, 173, 333 and 606 were    from one PCR product; nucleotide 640 was from one PCR product; and    nucleotides 691 and 1191 was from the splice variant).

In additional embodiments the Disc1 nucleic acid contains at least 30,at least 60, or at least 90 contiguous nucleotides, where thenucleotides either encode amino acids spanning at least two exons, arepresent in two or more exons, or are complementary to nucleotidespresent in two or more exons. The amount of nucleic acid correspondingto a particular exon can vary. In different embodiments the Disc1nucleic acid encodes a polypeptide containing at least 9, at least 10,at least 20, or at least 40 contiguous amino acids from two or moredifferent exons; and the Disc1 nucleic acid contains at least 15, atleast 30, or at least 45 contiguous bases from two or more differentexons, or the complement thereof.

Table 1 illustrates the intron/exon boundaries and genomic structure ofthe Disc1 gene. TABLE 1 Intron Exon Position Size Exon Boundary ExonSize bp^(a) In message^(b) in bp^(a) Splice Acceptor Site SequenceSplice Donor Site  1  1-90 >48,000 .........GCGCAGgtagggcccggggttctggaggagg SEQ ID NO: 21  2 992   91-1082 >1.9acactgttttctcttctcttctcag ACAGTG...CTGGAG gtgtgtgtgcttctggaatcgggtc SEQID NO: 7 SEQ ID NO: 22  3  70 1083-1152 34,050 atgtttccctttctcacccacacagGTCACT...ATACTG gtgagtccaaagctgttcgtagaca SEQ ID NO: 8 SEQ ID NO: 23  4148 1153-1300 7,422 tgcttttacctctttgggtttccag CAGAGA...CCAAAGgtgagtacccgtggatgccaccaca SEQ ID NO: 9 SEQ ID NO: 24  5 121 1301-14213,087 accaatgcatgtctgttacttgaag GGCCGG...TTGCAGgtgagtggaatagaatcttccagaa SEQ ID NO: 10 SEQ ID NO: 25  6 2361422-1657 >12,900 atctgttccccctctctctctgcag AAGGAA...CAGGAGgtactggtgactttctgagtttcca SEQ ID NO: 11 SEQ ID NO: 26  7  55 1658-17126541 caatgctcctttctaatttctctag CCTCCG...GCTCAG gtaagcccaccctcctcccattttcSEQ ID NO: 12 SEQ ID NO: 27  8 103 1713-1815 >9400ttgattctgccgtttctcctggcag GTGTGC...TATCAG gtaactgcagaggcacttatattca SEQID NO: 13 SEQ ID NO: 28  9 189 1816-2004 >51,900tcctctctcccccactgtgttgcag GAAGCT...CCCACA gtgagtagcccccagccaaagcctc SEQID NO: 14 SEQ ID NO: 29 10  61 2005-2065 14,626tgctcacgttgggtttttcttgcag AAACAC...GAGCAG gtaagttgtgtgtgtgtgtgggggg SEQID NO: 15 SEQ ID NO: 30 11 274 2066-2339 17,890ccatgcctgccttcctctgtcgtag CTGCAG...AAAGAG gtttgtcctgtgtgtatggctttgt SEQID NO: 16 SEQ ID NO: 31 12 118 2340-2457 9949 gacacatctctcattctctgaccagGATTCT...TCTTTC atatccttttcagtctctcgggaat SEQ ID NO: 17 SEQ ID NO: 32 13137 2458-2594 444 ttgtgtgctccttaacaatgtctac AGTCTC...TGAGGTgtgagtgtggagggggacgggggag SEQ ID NO: 18 SEQ ID NO: 33 14 263 2595-285724 ttttctttctttctttttccttcag CCTGCT...TGCTGC tgtcgccgccgccaccaccaccacSEQ ID NO: 19 SEQ ID NO: 34 15 302 2858-3159 tgtcgccgccgccaccaccaccacCACCAC... SEQ ID NO: 20^(a)base pair(s)^(b)The nucleotide position of the exons in the Disc1 message areindicated with the A of ATG being +1.

Nucleic acid having a desired sequence can be synthesized using chemicaland biochemical techniques. Examples of chemical techniques aredescribed in Ausubel, Current Protocols in Molecular Biology, JohnWiley, 1987-1998, and Sambrook et al., in Molecular Cloning, ALaboratory Manual, 2^(nd) Edition, Cold Spring Harbor Laboratory Press,1989.

Starting with a particular amino acid sequence and the known degeneracyof the genetic code, a large number of different encoding nucleic acidsequences can be obtained. The degeneracy of the genetic code arisesbecause almost all amino acids are encoded by different combinations ofnucleotide triplets or “codons”. Amino acids are encoded by codons asfollows:

-   A=Ala=Alanine: codons GCA, GCC, GCG, GCU-   C=Cys=Cysteine: codons UGC, UGU-   D=Asp=Aspartic acid: codons GAC, GAU-   E=Glu=Glutamic acid: codons GAA, GAG-   F=Phe=Phenylalanine: codons UUC, UUU-   G=Gly=Glycine: codons GGA, GGC, GGG, GGU-   H=His=Histidine: codons CAC, CAU-   I=Ile=Isoleucine: codons AUA, AUC, AUU-   K=Lys=Lysine: codons AAA, AAG-   L=Leu=Leucine: codons UUA, UUG, CUA, CUC, CUG, CUU-   M=Met=Methionine: codon AUG-   N=Asn=Asparagine: codons AAC, AAU-   P=Pro=Proline: codons CCA, CCC, CCG, CCU-   Q=Gln=Glutamine: codons CAA, CAG-   R=Arg=Arginine: codons AGA, AGG, CGA, CGC, CGG, CGU-   S=Ser=Serine: codons AGC, AGU, UCA, UCC, UCG, UCU-   T=Thr=Threonine: codons ACA, ACC, ACG, ACU-   V=Val=Valine: codons GUA, GUC, GUG, GUU-   W=Trp=Tryptophan: codon UGG-   Y=Tyr=Tyrosine: codons UAC, UAU

Biochemical synthesis techniques involve the use of a nucleic acidtemplate and appropriate enzymes such as DNA and/or RNA polymerases.Examples of such techniques include in vitro amplification techniquessuch as PCR and transcription based amplification, and in vivo nucleicacid replication. Examples of suitable techniques are provided byAusubel, Current Protocols in Molecular Biology, John Wiley, 1987-1998,Sambrook et al., Molecular Cloning, A Laboratory Manual, 2^(nd) Edition,Cold Spring Harbor Laboratory Press, 1989, and Kacian et al., U.S. Pat.No. 5,480,784.

V. Obtaining Additional Nucleic Acid Related To Disc1

The guidance provided herein can be used to obtain nucleic acidsequences encoding Disc1 related polypeptides from different sources.Obtaining such nucleic acids is facilitated using probes and primers andby the proper selection of hybridization conditions.

Probes and primers can be designed based on Disc1 nucleic acid and aminoacid sequences. Adjusting hybridization conditions is useful forcontrolling probe or primer specificity.

Techniques employed for hybridization detection and PCR cloning are wellknown in the art. Nucleic acid detection techniques are described, forexample, in Sambrook et al., Molecular Cloning, A Laboratory Manual,2^(nd) Edition, Cold Spring Harbor Laboratory Press, 1989. PCR cloningtechniques are described, for example, in White, Methods in MolecularCloning, volume 67, Humana Press, 1997.

Disc1 probes and primers can be used to screen nucleic acid librariescontaining, for example, genomic DNA or cDNA. Such libraries arecommercially available, and can be produced using techniques such asthose described in Ausubel, Current Protocols in Molecular Biology, JohnWiley, 1987-1998.

VI. Disc1 Probes

Disc1 probes contain a region that can specifically hybridize to Disc1target nucleic acid under appropriate hybridization conditions and candistinguish Disc1 nucleic acid from non-target nucleic acids. Probes forDisc1 can also contain nucleic acid that are not complementary to Disc1nucleic acid.

Probes can be free in solution or attached to a solid support. Probescovalently or non-covalently attached to a solid support can be used,for example, to monitor expression of different genes. Probes can beattached to a solid support through different techniques such asspotting synthesized probe onto a support or synthesizing probes in astepwise fashion onto a support. Techniques for monitoring geneexpression can be found in references such as U.S. Pat. No. 5,965,352and U.S. Pat. No. 6,203,987.

Probes are composed of nucleic acids or derivatives thereof such asmodified nucleic acid and peptide nucleic acid. Modified nucleic acidincludes nucleic acid with one or more altered sugar groups, alteredinternucleotide linkages, and/or altered nucleotide purine or pyrimidinebases. References describing modified nucleic acid include WO 98/02582,U.S. Pat. No. 5,859,221 and U.S. Pat. No. 5,852,188, each of which arehereby incorporated by reference herein.

Hybridization occurs through complementary nucleotide bases.Hybridization conditions determine whether two molecules, or regions,have sufficiently strong interactions with each other to form a stablehybrid.

The degree of interaction between two molecules that hybridize togetheris reflected by the Tm of the produced hybrid. The higher the Tm thestronger the interactions and the more stable the hybrid. Tm is affectedby different factors well known in the art such as the degree ofcomplementarity, the type of complementary bases present (e.g., A-Thybridization versus G-C hybridization), the presence of modifiednucleic acid, and solution components. (E.g., Sambrook et al., MolecularCloning, A Laboratory Manual, 2^(nd) Edition, Cold Spring HarborLaboratory Press, 1989.)

Stable hybrids are formed when the Tm of a hybrid is greater than thetemperature employed under a particular set of hybridization assayconditions. The degree of specificity of a probe can be varied byadjusting the hybridization stringency conditions. Detecting probehybridization is facilitated through the use of a detectable label.Examples of detectable labels include luminescent, enzymatic, andradioactive labels.

VII. Recombinant Expression

Disc1 polypeptides can be expressed from recombinant nucleic acid in asuitable host, or in a test tube using a translation system. Preferably,expression is achieved in a host cell using an expression vector.

An expression vector contains recombinant nucleic acid that includes aregion encoding a polypeptide along with regulatory elements for propertranscription and processing. The regulatory elements that may bepresent include those naturally associated with the recombinant nucleicacid and exogenous regulatory elements not naturally associated with therecombinant nucleic acid. Exogenous regulatory elements such as anexogenous promoter can be useful for expressing recombinant nucleic acidin a particular host.

Generally, the regulatory elements that are present in an expressionvector include a transcriptional promoter, a ribosome binding site, aterminator, and an optionally present operator. Another preferredelement is a polyadenylation signal providing for processing ineukaryotic cells. Preferably, an expression vector also contains anorigin of replication for autonomous replication in a host cell, aselectable marker, a limited number of useful restriction enzyme sites,and a potential for high copy number. Examples of expression vectors arecloning vectors, modified cloning vectors, specifically designedplasmids and viruses.

Expression vectors providing suitable levels of polypeptide expressionin different hosts are well known in the art. Mammalian expressionvectors well known in the art include pcDNA3 (Invitrogen), pMC1neo(Stratagene), pXT1 (Stratagene), pSG5 (Stratagene), EBO-pSV2-neo (ATCC37593), pBPV-1(8-2) (ATCC 37110), pdBPV-MMTneo(342-12) (ATCC 37224),pRSVgpt (ATCC 37199), pRSVneo (ATCC 37198), pSV2-dhfr (ATCC 37146),pUCTag (ATCC 37460), pCI-neo (Promega) and .lambda.ZD35 (ATCC 37565).Bacterial expression vectors well known in the art include pET11a(Novagen), lambda gt11 (Invitrogen), pcDNAII (Invitrogen), and pKK223-3(Pharmacia). Fungal cell expression vectors well known in the artinclude pYES2 (Invitrogen) and Pichia expression vector (Invitrogen).Insect cell expression vectors well known in the art include Blue BacIII (Invitrogen).

Recombinant host cells may be prokaryotic or eukaryotic. Examples ofrecombinant host cells include the following: bacteria such as E. coli;fungal cells such as yeast; mammalian cells such as human, bovine,porcine, monkey and rodent; and insect cells such as Drosophila andsilkworm derived cell lines. Commercially available mammalian cell linesinclude L cells L-M(TK.sup.-) (ATCC CCL 1.3), L cells L-M (ATCC CCL1.2), 293 (ATCC CRL 1573), Raji (ATCC CCL 86), CV-1 (ATCC CCL 70), COS-1(ATCC CRL 1650), COS-7 (ATCC CRL 1651), CHO-K1 (ATCC CCL 61), 3T3 (ATCCCCL 92), NIH/3T3 (ATCC CRL 1658), HeLa (ATCC CCL 2), C127I (ATCC CRL1616), BS-C-1 (ATCC CCL 26) and MRC-5 (ATCC CCL 171).

To enhance expression in a particular host it may be useful to modify aparticular encoding sequence to take into account codon usage of thehost. Codon usage of different organisms are well known in the art.(See, Ausubel, Current Protocols in Molecular Biology, John Wiley,1987-1998, Supplement 33 Appendix 1C.)

Expression vectors may be introduced into host cells using standardtechniques. Examples of such techniques include transformation,transfection, lipofection, protoplast fusion, and electroporation.

Nucleic acid encoding a polypeptide can be expressed in a cell withoutthe use of an expression vector. Additionally, mRNA can be translated invarious cell-free systems such as wheat germ extracts and reticulocyteextracts, as well as in cell based systems, such as frog oocytes.Introduction of mRNA into cell based systems can be achieved, forexample, by microinjection.

VIII. Production of Disc1 Deficient and Transgenic Mice

Based on the guidance provided herein, different types of mice which aredeficient in Disc1, or overexpress wild type, truncated, or otherwisemutant Disc1 (referred to as knockout, transgenic, or knock-in mice),can be produced. Such mice may mimic the truncation present in humanschizophrenics with DISC1 truncation reported by Millar et al. (2000),thus producing a mouse model for aspects of the human schizophrenicphenotype or schizophrenia as a whole. A scheme for producing Disc1deficient mice involves producing male and female mice with an alteredDisc1 allele and breeding the mice to produce mice having alterations inboth alleles.

Techniques for producing mice with an altered genome are well known inthe art. (Ausubel, Chapter 23, Manipulating the Mouse Genome, CurrentProtocols in Molecular Biology, John Wiley, 2001). An example of ascheme for producing a mouse with an altered Disc1 allele involves thefollowing:

-   -   (a) altering the Disc1 allele in a mouse embryonic stem cell by        homologous recombination with a transgene to produce an altered        embryonic stem cell;    -   (b) introducing the altered embryonic stem cell into a mouse        blastocyst to produce an altered blastocyst;    -   (c) introducing the altered blastocyst into a pseudopregnant        mouse to produce a pregnant mouse;    -   (d) allowing the pregnant mouse to produce offspring; and    -   (e) screening the offspring for the presence of an altered Disc1        allele to identify a Disc1 deficient mouse.

Genetic elements involved in gene expression include transcription andtranslation elements such as a promoter, splicing sites, polyadenylationregion, and ribosome binding site. Removing or altering these elementswill alter the production of Disc1 protein from the Disc1 gene.

Disc1 structural gene alterations can be used to substantially reduce oreliminate full-length expression of the polypeptide from the allele.Preferred alterations to the Disc1 structural gene involve eitherknocking out the gene or producing a gene that encodes bases 1-593corresponding to the amino region up to the translocation break point.

A deletion in a Disc1 allele can be accompanied by an insertion ofadditional nucleic acid. Additional nucleic acid that may be insertedincludes nucleic acid encoding a selectable marker having an independentpromoter and nucleic acid encoding a reporter protein transcriptionallycoupled to the Disc1 promoter. Examples of reporter protein that can beused in chimeric mice are β-galactosidase (lacZ) and green fluorescentprotein (GFP) and its derivatives.

Initial alterations are preferably produced using a transgene containingone or more selectable makers and nucleic acid targeting Disc1 forinsertion by homologous recombination. Homologous recombination can beperformed to create alterations in Disc1 and/or remove Disc1 regions.Markers can be used to facilitate screening for the insertion into amouse genome, and for the insertion occurring by homologousrecombination. (Ausubel, Chapter 23, Manipulating the Mouse Genome,Current Protocols in Molecular Biology, John Wiley, 2001.)

A transgene used for homologous recombination may contain recombinasesystems, which may be employed to excise inserted nucleic acid. Examplesof recombinase systems include the bacteriophage recombinase Cre/loxPsystem and the yeast recombinase Flp/FRT system. (Ausubel, Chapter 23,Manipulating the Mouse Genome, Current Protocols in Molecular Biology,John Wiley, 2001, and U.S. Pat. No. 5,564,182.) loxP recognition sitescan be positioned 3′ and 5′ of a region to be removed and excised by Crerecombinase. Similarly, frt recognition sites can be positioned 3′ and5′ of a region to be removed and excised by Flp recombinase.

Screening for mice containing an altered Disc1 allele can be achievedusing techniques such as those measuring the production of Disc1 mRNAtranscripts and whether any produced Disc1 transcript is different fromwild-type transcript. Techniques for measuring Disc1 MRNA transcriptsand the type of transcript include nucleic acid hybridization analysissuch as a Southern analysis that can detect the production and size oftranscripts, and the use of smaller nucleic acid probes specific for aparticular sequence. PCR can also be employed to measure Disc1 mRNAtranscripts. Western blotting and immunohistochemistry can also be usedto detect any full length or partial Disc1 protein in these animals.

EXAMPLES

Examples are provided below to further illustrate different features ofthe present invention. The examples also illustrate useful methodologyfor practicing the invention. These examples do not limit the claimedinvention.

Example 1 Materials and Methods

This example describes different materials and methods that wereemployed to clone and study Disc1.

Genomic Identification

Bioinformatic analysis of the draft mouse genomic sequence identifiedfour mouse genomic sequences with homology to the human DISC1. The mousesequences were identified by searching public mouse genomic shotgunsequences employing Blast (Altschul et al., (1997) Nucleic Acids Res,25(17), 3389-402).

cDNA Cloning

Primers were designed based on mouse genomic sequences. A 1779 bp and a1590 bp product were obtained by PCR using either mouse heart or brainMarathon-Ready cDNA (Clontech) as template and primersTTCATCCAACTCTCCCTTGG (SEQ ID NO: 35) and GAGAGCTTCGTCGTGACTG (SEQ ID NO:36). PCR was carried out using Pfu Turbo DNA polymerase (Stratagene).Each 50 μl reaction contained 2.5 U of enzyme, 0.2 μM of each primer,0.2 mM of each dNTP, 10 mM KCl, 10 mM (NH₄)₂SO₄, 20 mM Tris-Cl (pH8.75), 20 mM MgSO₄, 0.1% Triton X-100, 0.1 mg/ml BSA and 2% DMSO. Thereaction utilized 35 cycles with a denaturation step of 20 seconds at94° C., an annealing step of 1 minute at 60° C., and a synthesis step of3 minutes at 72° C. The PCR products have been cloned into PCR-BluntII-TOPO vector (Invitrogen) using standard methods and sequenced.

5′RACE (Rapid Amplification of cDNA Ends) products were obtained usingthe Pfu Turbo DNA polymerase and the same reaction buffer describedabove. The PCR amplification was done with 32 cycles with a denaturationstep of 20 seconds at 94° C., an annealing and synthesis step of 3minutes at 68° C., with mouse heart brain Marathon-Ready cDNA (Clontech)as template (gene-specific primer CATTCTGGTTGCCTGCTGCTGC) (SEQ ID NO:37). It was followed by a nested PCR reaction using primerACCTGAGCCAAGTCTGCCAAGC (SEQ ID NO: 38) with 25 amplification cycles. ThePCR products have been cloned into PCR-Blunt II-TOPO vector (Invitrogen)using standard methods and sequenced.

3′RACE products were obtained using the Pfu Turbo DNA polymerase andsame reaction buffer above except excluding DMSO. PCR amplification wasrun using 32 cycles with a denaturation step of 20 seconds at 94° C., anannealing and synthesis step of 3 minutes at 68° C., with mouse heartbrain Marathon-Ready cDNA (Clontech) as template (gene-specific primerCTGCTGAAGTTGGAGAAAAGTGCG) (SEQ ID NO: 39). It was followed by a nestedPCR reaction using primers GGCCATGTACAGTCACGACGAAG (SEQ ID NO: 40) orGAGCTCCAGACGGTGAAGGAAAC (SEQ ID NO: 41) with 25 cycles. The PCR productshave been cloned into PCR-Blunt II-TOPO vector (Invitrogen) usingstandard methods and sequenced.

Genomic Structure

A 3′ mouse Disc1 cDNA sequence (nucleotides 2376-2490) was used as aprobe to screen a BAC (Bacterial Artificial Chromosome) Mouse library(Incyte Genomics). Standard procedures were used for hybridization asrecommended by the manufacturer. Double-stranded probe was labeled with[α-³²P]dCTP using rediprimer II (Amersham Pharmacia Biotech rediprimerII random prime labeling system) and purified using PrincetonSeparations Centri-Sep columns.

The positive BAC clone was confirmed by PCR (primer set 1,GGATTCTCACATCGTTTCTGC (SEQ ID NO: 42) and GAGAGCTTCGTCGTGACTG (SEQ IDNO: 43); primer set 2, GAAATGGCCACTATACCTGC (SEQ ID NO: 44) andCGGCAGCAGTGGTTGTGA) (SEQ ID NO: 45). PCR was carried out using AmpliTaqGold DNA polymerase (Applied Biosystems). Each 50 μl reaction contained1.25 U of enzyme, 0.2 μM of each primer, 0.2 mM of each dNTP, 10 mMTris-Cl (pH 8.3), 50 mM KCl, 1.5 mM MgCl₂, 0.001% (w/v)gelatin.Following 9 minutes incubation at 94° C., the reaction utilized 32cycles with a denaturation step of 20 seconds at 94° C., an annealingstep of 30 seconds at 60° C., and a synthesis step of 1 minute at 72° C.

The TRAX gene is located upstream from DISC1 on human chromosome 1q42.PCR results showed one of the mouse BAC clone positive for 3′ mouse TRAXis also positive for 5′ mouse Disc1 by PCR. Primers CCACATGCTTTCAACGAGTT(SEQ ID NO: 46) and AGAGCAGGTACCAGGACTGAC (SEQ ID NO: 47) were used forTsnax. Two Disc1 primer sets were used (set 1, TTCATCCAACTCTCCCTTGG (SEQID NO: 48) and GGGCCTGTCTGAGCTAGATG (SEQ ID NO: 49); set 2,AGACTTGGCTCAGGTGACGA (SEQ ID NO: 50) and GCGGTTGCTCAGTAGGTAG) (SEQ IDNO: 51). PCR conditions were as same as above.

Northern Blot Analysis

Clontech mouse multiple tissue were probed with Disc1 (nucleotides2376-2490). The probe was obtained by PCR using mouse heartMarathon-Ready cDNA (Clontech) as template. Disc1 is weakly present astranscripts of ˜7 kb and ˜4.4 kb in heart, brain, kidney and testis.

Low stringency hybridization was carried out on Clontech rat multipletissue northern blots at 60° C. A probe corresponding to nucleotides1138-2497 of Disc1 was obtained by excising one of the Disc1 heart cDNAclones using HindIII and EcoR1. A ˜7 kb transcript showed in heart, andskeletal muscle, and another ˜1.35 kb transcript showed in heart, liver,kidney and brain. Expression level was higher in heart and liver than inskeletal muscle and brain.

Bioinformatic Analysis

Two BACs were identified from the TIGR BAC end sequencing project bysubmitting murine TRAX cDNA sequence to the database www.tigr.org. (Zhaoet al. (2001) Genome Res, 11(10), 1736-1745.)

Human DISC1 and mouse Disc1 DNA and protein sequences were aligned usinga Clustal W program. (Thompson et al., (1994) Nucleic Acids Res, 22(22),4673-80.) The human and murine sequences were characterized forsubsequences using PROSITE. (Bairoch, (1991) Nucleic Acids Res,19(Suppl), 2241-2245, Henikoff et al., (1991) Nucleic Acids Res, 19(23),6565-6572.) Human and murine DISC1 sequences were both positive forleucine zipper motifs. Homologies to DUF232, tropomyosin and bipartitenuclear localization signal were found by searching the murine or humansequence using the InterPro program. (Apweiler et al. (2000)Bioinformatics, 16(12), 1145-1150.)

In Situ Hybridization

C57BL6 male mice (20-25 g; Taconic; Germantown, N.Y.) were housed in theanimal care facility (AAALAC certified) with a 12-hour light, 12-hourdark photoperiod and free access to tap water and rodent chow. Afteracclimation (5-10 days), the animals were euthanized with an overdose ofCO₂, their brains frozen and 20 μm coronal cryostat sections collectedon gelatin-coated slides.

A fragment (bases 1138-2497) of the mouse Disc1 was excised from a heartcDNA clone with HindIII and EcoRI and subcloned into a pBluscript vector(Stratagene, La Jolla, Calif.). The plasmid was then used to generate³⁵S-UTP labeled cRNA probes for in situ hybridization.

Briefly, the section-mounted slides were postfixed in 4%paraformaldehyde, treated with acetic anhydride and then delipidated anddehydrated with chloroform and ethanol. The slides were then hybridizedwith 200 μl (6×10⁶ DPM/slide) of an antisense or sense (control)riboprobe for Disc1 mRNA in a 50% formamide hybridization mix andincubated overnight at 55° C. in a humidified slide chamber withoutcoverslipping. In the morning, the slides were washed in 2×SSC/10 mMDTT, treated with RNase A (20 μg/ml) and washed in 67° C. in 0.1×SSC toremove nonspecific label. After dehydration, the slides were opposed toBioMax (BMR-1; Kodak) x-ray film for 3 days and then dipped in NTB2nuclear emulsion. The slides were exposed for 4-6 weeks,photographically processed, stained in cresyl violet and cover-slipped.

Example 2 Cloning of Disc1

Searching the DISC1 protein sequence against the public mouse genomicdatabase (http://www.ncbi.nlm.nih.gov/genome/seq/MmHome.html) identifiedfour mouse genomic DNA sequences corresponding to DISC1 sequences (Table2). These sequences corresponded to exons 2, 6, 12 and 13 of the humanDISC1 genomic sequence. (Millar et al. (2001) Mol Psychiatry, 6(2),173-178.) Primers against mouse genomic fragments 1 and 4 were used toPCR amplify the central portion of the Disc1 from both whole brain andheart cDNA libraries. 5′ and 3′ RACE were then used to obtain the restof the orthologous Disc1 sequence. TABLE 2 Amino Acid in Amino Acid inHuman Human Exon Mouse Genomic 123-322 Exon 2 133-322 sequence 1 Genomic465-544 Exon 6 461-540 sequence 2 Genomic 769-807 Exon 12 768-806sequence 3 Genomic 808-842 Exon 13 807-840 sequence 4

The Disc1 cDNA is 3190 bp in length, with an open reading frame of 2553bp, corresponding to a protein 851 amino acids in length. An in-framesplice variant was also identified (SEQ ID NOs: 3 and 4).

The splice variant is 3001 bp in length, with 189 base pairs deletedcompared to the full-length mouse cDNA. With nucleotide +1 being fromthe ATG, nucleotides +1843 to +2031 are spliced out in this variant; ithas an open reading of 2364 bp, corresponding to a protein 788 aminoacids in length.

A splice variant of human DISC1 was previously identified. (Millar etal. (2000) Hum. Mol. Genet, 9(9), 1415-23.) However, it is in adifferent location in the gene than the Disc1 splice variant. Both thefull-length Disc1 sequence and the splice variant sequence wereamplified in the brain and the heart cDNA libraries.

Multiple single nucleotide polymorphisms (SNPs) were also identifiedduring the cloning of Disc1 (Table 3) TABLE 3 Single NucleotidePolymorphisms Position Nucleotide (A in ATG is +1) Change Amino Acid 137C → T A → V 173 G → A G → D 333 G → T E → D 606 C → T P → P 640 T → C F→ L  691* T → C C → R 1191* G → A Q → Q*polymorphism found in splice variantThe polymorphisms at positions 137, 173, 333, 606 are from the same PCRproduct and the polymorphism at position 640 is from a different PCRproduct.

Example 3 Bioinformatic Analysis

Clustal W (Thompson et al. (1994) Nucleic Acids Res, 22(22), 4673-4680)alignment of the human and murine DNA sequences revealed 60% identitybetween the sequences. Protein alignment between the human and mouseprotein sequences (FIG. 1) demonstrated 56% identity and 14% similarity(excludes identical amino acids) between the protein sequences. This isa lower degree of homology than is typically seen between mouse andhuman orthologs. (Makalowski et al. (1996) Genome Res, 6(9), 846-857.)

Bioinformatic analysis using PROSFIE revealed that three leucine zippermotifs seen in the human DISC1 sequence are conserved in the mouse.Bioinformatic analysis techniques are described by Landschulz et al.(1988) Science, 240(4860), 1759-1764, Bairoch (1991) Nucleic Acids Res,19(Suppl), 2241-2245, and Henikoff et al. (1991) Nucleic Acids Res,19(23), 6565-6572. The leucine zipper motifs were located as follows:amino acids 454-475, amino acids 461-482 and amino acids 603-624 inDisc1 and amino acids 458-479, amino acids 465-486, and amino acids607-628 in DISC1.

The potential coiled-coil domain in the C-terminal end of the humanDISC1 protein previously described (Millar et al. (2000) Hum. Mol.Genet., 9(9), 1415-1423), is also conserved in the mouse protein. Inaddition, InterproScan database (Apweiler, et al. (2000) Bioinformatics,16(12), 1145-1150) searching of the mouse sequence revealed a lowhomology to a putative prefolding chaperone, DUF23 (Mori et al. (1998)J. Biol. Chem, 273(45), 29794-29800). In contrast, neither the suggestedbipartite nuclear localization signal (Dingwall et al. (1986) Annu. Rev.Cell. Biol., 2, 367-390), or the weak homology to tropomysoin (MacLeod(1987) 6(5), 208-212) found in human DISC1 were found in Disc1.

Example 4 Disc1 Chromosomal Localization

Due to the low homology level between the mouse Dis1 and human DISC1sequence, mouse genomic sequence was examined to verify that it was thetrue ortholog of DISC1 by demonstrating that the cloned Disc1 genesequence came from the syntenic region corresponding to human chromosome1q42 in the mouse genome. TRAX (Translin-associated Factor X; Tsnax,NM_(—)016909) has been verified to be 35 kb (kilobase) proximal to thehuman DISC1 sequence on chromosome 1. (Millar et al. (2000) Genomics,67(1), 69-77.)

Mouse BACs were identified by searching the TIGR mouse BAC endsequencing database with the mouse TRAX (Tsnax, NM_(—)016909) sequence(www.tigr.org). (Zhao et al. (2001). Genome Res, 11(10), 1736-1745.)

Two BACs were identified that contained Tsnax sequence. BAC 418L11contained nucleotides 964-1446 and BAC 236F19 contained nucleotides1500-2410 of Tsnax (FIG. 5). A BAC containing Disc1 sequence, 259E12,was also identified by hybridization of a Disc1 probe against an ES BAClibrary.

To confirm that Tsnax was located proximal to Disc1 in the mouse genome,PCR amplification using primers from Tsnax and Disc1 was performed oneach of the identified BACs. 418L11 was positive for Tsnax DNA sequencefor amino acids (aa) 733-983 whereas it was negative for Tsnax sequence3′ using Tsnax DNA primers for aa1524-1660. 236F19 contains genomicmouse sequence distal to 418L11. PCR results demonstrated that it wasnegative for Tsnax sequence for aa1524-1660, but positive for Tsnaxsequence aa2036-2258. In addition, 236F19 was positive for Disc1sequence using primers for aa640-771 and aa828-1035. This resultdemonstrated that Disc1 was the true ortholog of DISC1 because it was inthe mouse syntenic region corresponding to human chromosome 1q42.

Example 5 Northern Analysis

Disc1 probe was hybridized against a Clontech mouse multiple tissuenorthern blot. With low-stringency washing conditions, Disc1 transcriptswere identified in heart, brain, kidney and testis. The heart hadtranscripts at 7.0 and 4.4 kb, testis at 10 and 4.4 kb and kidney hadone transcript at 4.4 kb. A faint transcript was also identified in thebrain at 7.0 kb. The Disc1 probe was also hybridized against a Clontechrat multiple tissue northern blot. With low-stringency washingconditions, Disc1 transcripts were identified in the heart, brain,liver, skeletal muscle, kidney and testis. Upon higher stringencywashing, only the heart transcript at 7.0 kb was identified.

Example 6 In Situ Hybridization

In situ hybridization analysis was performed on adult mouse brain usinga Disc1 riboprobe on C57BL6 mice brain sections. High level ofexpression was seen in the dentate gyrus of the hippocampus, with lowerlevel expression in the olfactory bulbs, cerebellum, and CA1, CA2 andCA3 fields of the hippocampus.

Other embodiments are within the following claims. While severalembodiments have been shown and described, various modifications may bemade without departing from the spirit and scope of the presentinvention.

1. A purified polypeptide comprising at least 18 contiguous amino acidsof SEQ ID NO:
 1. 2. The polypeptide of claim 1, wherein said polypeptidecomprises at least 50 contiguous amino acids of SEQ ID NO:
 1. 3. Thepolypeptide of claim 1, wherein said polypeptide comprises at least 9contiguous amino acids of two or more contiguous exon encoded regionsselected from the group consisting of: exon 1-exon 2; exon 2-exon 3;exon 3-exon 4; exon 4-exon 5; exon 5-exon 6; exon 6-exon 7; exon 7-exon8; exon 8-exon 9; exon 9-exon 10; exon 10-exon 11; exon 11-exon 12; andexon 12-exon
 13. 4. The polypeptide of claim 1, wherein said polypeptidecomprises the amino acid sequence of SEQ ID NO: 1, SEQ ID NO: 3, or amodified SEQ ID NO: 1, wherein said modified SEQ ID NO: 1 contains oneor more modifications selected from the group consisting of: amino acid46: A to V; amino acid 58: G to D; amino acid 111: E to D; amino acid214: F to L; and amino acid 231: C to R.
 5. The polypeptide of claim 1,wherein said polypeptide consists of the amino acid sequence of SEQ IDNO: 1, SEQ ID NO: 3, or a modified SEQ ID NO: 1, wherein said modifiedSEQ ID NO: 1 contains one or more modifications selected from the groupconsisting of: amino acid 46: A to V; amino acid 58: G to D; amino acid111: E to D; amino acid 214: F to L; and amino acid 231: C to R.
 6. Thepolypeptide of claim 1, wherein said polypeptide consists of the aminoacid sequence of SEQ ID NO:
 1. 7. A recombinant nucleic acid comprisinga nucleotide sequence that either: a) encodes the polypeptide of claim 1and is transcriptionally coupled to an exogenous promoter; b) is atleast 30 contiguous bases present in SEQ ID NO: 2 or the complementthereof, and is attached to a solid support; c) is SEQ ID NO: 2; d) is amodified SEQ ID NO: 2, wherein said modified SEQ ID NO: 2 contains oneor more modifications selected from the group consisting of: nucleotide137: C to T; nucleotide 173: G to A; nucleotide 333: G to T; nucleotide606: C to T; nucleotide 640: T to C; nucleotide 691: T to C; andnucleotide 1191: G to A; and e) is SEQ ID NO:
 4. 8. The recombinantnucleic acid of claim 7, wherein said nucleotide sequence is either SEQID NO: 2, SEQ ID NO: 4, or is a modified SEQ ID NO: 2, wherein saidmodified SEQ ID NO: 2 contains one or more modifications selected fromthe group consisting of: nucleotide 137: C to T; nucleotide 173: G to A;nucleotide 333: G to T; nucleotide 606: C to T; nucleotide 640: T to C;nucleotide 691: T to C; and nucleotide 1191: G to A; and said nucleotidesequence is transcriptionally coupled to an exogenous promoter.
 9. Therecombinant nucleic acid of claim 8, wherein said recombinant nucleicacid is an expression vector.
 10. A recombinant cell comprising therecombinant nucleic acid of claim 9, wherein said cell comprises an RNApolymerase recognized by said promoter.
 11. (canceled)
 12. A purifiedantibody preparation comprising an antibody that selectively binds to apolypeptide of SEQ ID NO: 1 over the human disrupted-in-schizophrenia 1polypeptide.
 13. A recombinant mouse comprising an alteration in anallele encoding a disrupted-in-schizophrenia 1 (Disc1) polypeptidecomprising at least 20 contiguous amino acids of SEQ ID NO: 1, whereinsaid alteration substantially reduces, or increases, full lengthexpression of said polypeptide from said allele.
 14. The recombinantmouse of claim 13, wherein said Disc1 polypeptide consists of SEQ ID NO:1, SEQ ID NO: 3, or a modified SEQ ID NO: 1, wherein said modified SEQID NO: 1 contains at least one modification selected from the groupconsisting of: amino acid 46: A to V; amino acid 58: G to D; amino acid111: E to D; amino acid 214: F to L; and amino acid 231: C to R.
 15. Therecombinant mouse of claim 13, wherein said alteration substantiallyeliminates expression of said polypeptide.
 16. The recombinant mouse ofclaim 13, wherein said alteration results in the production of atruncated polypeptide.
 17. The recombinant mouse of claim 13, whereinsaid mouse comprises alterations in both Disc1 alleles, wherein saidalterations substantially reduce full-length expression of saidpolypeptide from said allele. 18-19. (canceled)